Expected behavior and actual behavior:

Boot Rpi hardware capable of usb boot from an usb drive and not be able to see contents of '/' at http://box/usb

from: #2497

981 =IIAB==========================================================================
982 COMMAND: /bin/df -h # Disk usage
983
984 Filesystem Size Used Avail Use% Mounted on
985 /dev/root 917G 11G 860G 2% /
991 /dev/sda1 253M 54M 199M 22% /boot

995 =IIAB==========================================================================
996 COMMAND: /bin/lsblk # Partition mount points
997
998 NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
999 sda 8:0 0 931.5G 0 disk
1000 ├─sda1 8:1 0 256M 0 part /media/usb0
1001 └─sda2 8:2 0 931.3G 0 part /media/usb1

Steps to reproduce the problem:

see above and note the boot device is mounted at the usb share point

IIAB version, OS version, hardware details:

master as of 2497

Suggestions:

1. toggle local_vars iiab_usb_lib_show_all: to False, and document the effects of True
   or
2. add code to override the selection of True when usb-boot is detected, and note why the override is present